Bending pad structure and associated apparatus for bending tube



March 10, 1959 Filed June 10. 1953 D. R. KNOX ETAL BENDING PAD STRUCTUREAND ASSOCIATED APPARATUS FOR BENDING TUBE 7 Sheets-Sheet 1 JNVENTORS DA1Q. K/vox (i STANLEY .GO

\ Z'zav ATTOP/VEYS.

March 10, 1959 D. R. KNOX ETAL 2,876,323

BENDING PAD STRUCTURE AND ASSOCIATED APPARATUS FOR BENDING TUBE 7Sheets-Sheet 2 Filed J1me 10. 1953 c @lc INVENTORS DAVID E. /(\/0x 62ATTOQNEYS.

D. R. KNOX ETAL BENDING PAD STRUCTURE March 10, 1959 2,876,823 ANDASSOCIATED APPARATUS FOR BENDING TUBE '7 Sheets-Sheet 3 Filed June 10.1953 \ow .1 A E new Nike. N m m i v in: 8 A 1NW MM. Aw I WV 50 lav/WW NWRQN A L mX E mm m 3? 5 a v V. 6 WW March 10, 1959 D. R. KNOX EFAL2,876,823 BENDING PAD STRUCTURE AND ASSOCIATED APPARATUS FOR BEND INGTUBE Filed June 10. 1953 '7 Sheets-Sheet 4 75 M o (o 0) 3 (0 U 7 (o o)(o INVENTORS DA V/D Q. Kvox &

' STANLEY GONDEK,

aiiwwpcfl zzwfi ATTORNEYS March 10, 1959 D. R. KNOX ETAL BENDING PADSTRUCTURE AND ASSOCIATED APPARATUS FOR BENDING TUBE Filed June 10. 19537 Sheets-She et 5 INVENTORS DAVID E. Kvo

X 6c GONDEK.

' STANLEY ATTOENEYJ.

KNOX ET AL PAD STRUCTUR March 10, 1959 D. R.

- BENDING E AND ASSOCIATED APPARATUS FOR BENDING TUBE I .7 she etssheet's Filed June 10. 1953 INVENTORS Kvox 5:

DAVID E. STANLEY GOA/05K. av m fwaaaf ATTORNEYS.

United States Patent BENDING PAD STRUCTURE AND ASSOCIATED APPARATUS FORBENDING TUBE Application June 10, 1953, Serial No. 360,751

9 Claims. 01. 15346) This invention relates to an apparatus for bendingtube, and it is concerned particularly with apparatus and bendingelements particularly adapted to simultaneously bend a plurality oftubes, and for supporting the tubes to prevent substantial distortion ordeformation thereof during the bending operation.

While the apparatus may be employed for bending long work pieces otherthan tube, such, for example, as rods or the like, it is believed thatthe apparatus is most useful for bending tubes and, therefore, theinvention will be disclosed with reference to, and the apparatusdescribed with reference to, the bending of tubes.

There are a number of objects of the invention and one important objectis the provision of apparatus and bending elements for bending tube on ashort radius. In this connection, bending elements are provided forsupporting a plurality of tubes relatively'short-radius, the tubes areheld and supported so as to substantially prevent flattening of thetubes in cross section at the location of the bend. In this connection,the bending elements are so arranged that the several tubes support eachother.

A further object is to provide bending mechanism which substantiallyeliminates friction on the tubes as the bending devices fashion theplurality of tubes about a bending element or arbor. A still furtherobject of the invention is to provide articulating bending devices whichare grooved for receiving the tubes, so that the grooved devices mayshift into and out of engagement with the tubes to thus facilitateplacing the tubes in and removing the tubes from the bending apparatus.A still further object is to provide an improved construction foraccommodating the takeup in the length of the tubes due to the lengthwhich goes into or is absorbed in the bend.

In making reference to bending tube on a short radius, it is to beappreciated that the radius of the bend is relative to the diameter andwall thickness of the tube. What may be considered a small radius ofbend for a relatively large diameter tube, may not necessarily beconsidered a short radius bend for a tube of smaller diameter. A tubewith a relatively thick wall might be bent with facility on a givenradius but such a radius of bend might be considered a short radius fora tube with a thinner wall. In bending the tubes, say for example, about180, the metal of the tube on the outside of the bend is under tension,while the metal on the inside of the tube is under compression, theterms outside and inside being used with reference to the neutral axis.These conditions tend to cause the tube to become flattened as it isbent, particularly when a tube is bent on a radius relatively short whenconsidered in connection with gparatus for bending a plurality of tubesinto-serpentine so that, as they are bent on a the tube diameter andwall thickness. As stated above, the invention is con-' form and theapparatus disclosed herein is one for bending a plurality of tubes intoserpentine form. Some of the bending elements or devices, however, maybe employed for bending tubes other than in serpentine form.

Fig. 1 is a front elevational view illustrating a machine constructed inaccordance with the invention.

Fig. 2 is an enlarged elevational view with some parts broken away andsome parts in section showing some bending elements.

Fig. 3 is a view of the mechanism shown in Fig. 2 looking from the righthand side of Fig. 2.

Fig. 4 is a detailed sectional view taken on line 4-4 of Fig. 3 showinga movement limiting device.

Fig. 5 is a view of the apparatus shown in Fig. 2 illustrating theposition of parts after a bend has been made.

Fig. 6 is a generally elevational view, with some parts broken away,illustrating mechanism for accommodating takeup in the bending of thetube.

Fig. 7 is a sectional view taken substantially on line 77 of Fig. 6illustrating structural features;

Fig. 8 is a sectional view taken on line 8-8 of Fig.

I 6 showing structural features of a swinging arm.

Fig. 9 is a general elevational view illustrating an arbor and bendingdevice in position ready to perform a bend.

Fig. 10 is a sectional view taken on line 1010 of Fig. 9 showing anarbor and a bending device.

Fig. 11 is an enlarged sectional view showing a bending pad applied totubes to be bent.

Fig. 12 is a view of the apparatus shown in Fig. 9 showing the positionof the parts at the end of a tube bending operation.

Fig. 13 is a view similar to Fig. 5 showing the bending mechanism on theend of the arm in open position after a bending operation.

Fig. 14 is a diagrammatic view illustrating the posi'- tion of the tube,an arbor, and a bending pad at the completion of a bending operation.

Fig. 15 is a view of the apparatus shown in Fig. 14 showing the parts inopen position for releasing the bent tube.

Fig. 16 is a generally elevational view of the mechanism shown in Fig.12 showing the position of the parts after the tube is released.

Fig. 17 is a top plan view of the apparatus on approximately the samescale as Fig. 1.

Fig. 18 is a fragmentary plan view on an enlarged scale showingstructure of the swinging arm.

Fig. 19 is a fragmentary plan view on an enlarged scale showingstructure at the central portion of the apparatus. I The apparatus shownin Fig. 1 includes a suitable frame or base 1 withthe bending mechanismmounted thereon, and the tubes which are the work pieces are" shown atW. The tubes are fed to the machine from the right hand side of Fig. l.The work pieces are supported by a support 2, and further supported in aclip or holder 4 on an arm 5 which swings about a fulcrum 6 in'turnmounted for swinging on a vertical axis on support 2 as shown. A loadingdevice is generally illustrated at 8.

The several tubes are positioned as shown and the lead ing ends thereofmay be engaged by a clamp 10 operated hydraulically as by means of apiston in a cylinder 11'. After the first bending operation the clamp 10may not be used but the tubes may be held by placing a formed bend overa stud or post 14.

The machine has a generally cylindrical arbor 16 having a taperedsupporting extension 16a mounted upon shown inFigs. 1

an arbor carrying arm 18 which is pivoted as at 19 and which may beoperated through a swinging movement hydraulically as by means of apiston in a cylinder 20, a piston rod 21 of which is connected to thearm 18 as and- 17. Adjacent to andgenerally" under the arbor 16 is astationary tube bending shoe or plate 23 carried by a fixed bracket 24.The tubes are placed under the arbor 16 and over the fixed shoe 23 asshown in Fig. 9;

There is a bending device for bending the tubes about the arbor, in theform of a shoe 28 with a grooved bending pad 30 thereon (Fig. 10) andthe shoe has a bearing formation 31 journalled in a plate 32. This plate32 is pivotally mounted as at 33. The plate 32 has a lug 34 thereonarranged to engage an abutment 35 carried by fixed bracket 24 (Fig. 16)and to be held against the abutment by a lug 36 on the arm 18 (Fig. 12).There is a lever arm 38 rigidly formed with the bending element 28 andits bearing portion 31, which is provided on its end with a roller 40for operating in a closed cam slot 41 as will presently be seen, andwhich is also Provided with a roller 42. Cam slot 41 is formed in aplate 43 secured on a swinging arm to be described in greater detail. Itmight be stated at this point that the lever arm 38 serves to swing thebending device 28 about the bearing 31 so that it moves about the arborto bend the tubes.

There is a main rocker shaft 44 (Figs. 7 and 17) which may be rocked bymeans of a gear 45 mounted thereon and a rack 46 operated by a pistonrod 47 (Fig. l) of a piston in a hydraulic cylinder 48. This shaftcarries a swinging arm generally illustrated at 50. This arm hasrelatively slidable parts. The base part 51 thereof is keyed to rockwith the shaft 44. The slidable and extending part 52 is mounted on saidbase part 51 by guides 53 and 54 and acted upon by coil springs 56. Thecoil springs are carried by headed rods 57 slidably mounted on ears 58at the base end of the arm member 52. Springs 56 act on ears 58 and,through the heads on rods 57, react against adjusting screws 60 mountedin brackets 61 carried by the base part 51 of the arm. The arm member 52is provided with a roller 63 carried by a bracket 64 which may beadjustably set in position by a screw 66 and the roller engages thesurface of an open faced cam 65, the purpose of which will presentlyappear. The arm 52 carries the plate 43 containing cam 41. It will beseen, therefore, that if the arm 50 is swung counter-clockwise, as Figs.1 and 9 are viewed, the lever 38 is carried with the arm, and shoe 28with its bending pad 30 is moved about its fulcrum in plate 32.

In so doing, the several tubes which are in position, as indicated inFig. 10, are fashioned about the arbor 16. This will be described morefully later. The axis of the arm 50 is shown at x in Fig. 6, and it willbe seen that I this axis is removed from the working axis y of the arbor16.

An assembly embodying a support or bracket 70 (Figs. 2, 3, S and 13) ispivotally mounted as at 71 (Fig. 3) on a bearing structure 52a at theend of arm 52 and bracket 70 carries a generally cylindrical arbor 72andv a fixed bending pad 73. Arbor 72 has a lateral supporting taperedextension 72a. The, bracket has a sprocket 74 over which runs a chain75. Sprocket 74 is fixed on bracket. 70 by a bolted construction as at76.

The bracket 70 carries a rocker shaft 77 with a depending actuatinglever 78. Arms 80 and 81 mounted on the rocker shaft 77 support a pintlepin 82. A subassembly is rockably mounted on the pin 82 and it residesin a base member 84 and a bending pad 85 slidable upon the .base member,there being an interposed spring 86 which reacts on the base member andacts upon the bending pad to normally urge the slide member to the rightas Fig. 2 is viewed. The bending pad member is securedto the.basemernber 84 by interengaging sliding elements shown at 88. Thesub-assembly is acted upon by toggle levers 90 and 91 (Figs. 2 and 13)with an interposed spring 92. cludes a rocker arm 94with adjustablestops for engaging alimit stop member 95. Mounted: on tberocker arm 94.

mshattfllisa cam 2 in: engag usth memb r 4..aud-

Means to limit the rocking action .in-

the member 84 has a finger or projection 97 also for engaging the cam96. In the position shown in Fig. 2, the bending pad is set for abending operation. It will be noted that the cam 96 holds the bendingpad subassembly in position against the tubes. If the lever 78 beshifted counter-clockwise, as Fig. 2 is viewed, the cam 96 strikes thefinger 97 and rocks the sub-assembly about the pin 82, and the togglelevers shift to the dotted line position to hold the bending pad and thebase member 84 in an elevated and inclined position relative to. thearbor 72, said inclined position not being shown inv Fig. 2 butappearing in Fig. 13 after completion of a bending operation.

A means for operating the lever 78 conveniently takes the form of a rod100 (Figs. 1, 2 and '5) actuated by the piston rod 101 of a piston in acylinder 102; the rod has an abutment 104 for engaging the lever 78. Therod 100 also has an abutment 105v for engaging the lever 78in anotherposition thereof as will presently appear;

Mounted on the arm 50 is a sprocket over which the chain 75 operates.The sprocket is mounted on a stud 111 which passes through an opening113 in the arm section 51 and which is secured to the arm section 5.2.The sprocket 110 is fixedly secured as by means of screws 114 to anactuating arm 115 (Figs. 1, 6 and 9). This actuating arm may be formed,as shown in Fig. 1, for clearance purposes and is pivotally connected toa rod 116 in turn connected to a piston rod in a hydraulic cylinder 118pivotally mounted to the frame as at 119. The. chain 75 may be equippedwith a tightening screw 121 (Fig. 1) since the chain only has a slightoscillation relative to the sprockets.

The bending pad 30, for cooperation with the arbor 16., is acted upon bya spring (Figs. 1, 9, 12 and 1.6),, as sociated with the pad 30 byinterconnected levers 131and- 132. This spring normally holds the pad 30to the right as Fig. 9 is viewed.

It will be noted that the bending pad 30 is provided with a plurality ofgrooves 135, each for receiving av tube as shown in Figs. 10 and 11. Theside portions of the pad 30 as shown at 136 and 137 are of sufficientex-. tent as to project at least to, and preferably somewhat beyond themedian line or neutral axis of the outermost. tubes. The web portions138 defining the individual grooves are of lesser extent and do notextend tothe median line of the tubes. The grooves fit the tubes. asshown in Figs. 10 and 11 and, accordingly, the bending pad to be used ismade precisely for use with tubes of determined diameter. The severaltubes, accordingly,, contact and support each other along lines lyingsubstantially in a plane containing the neutral axes of the tubes. Asshown in Fig. 10, there are eight tubes in position each lying in agroove 135.

The, bending pad 85 is similarly constructed as, shown; in Fig. 3 thesame having a plurality of grooves 140,,onefor each tube, with theintervening web. portions 141 ter: minating short of a plane containingthe neutral axes of the tubes and with side portions 142 and 143 which;CD7: gage the outermost tubes at a plane containing their neu,- tral.axes. The pad 85, as shown in Fig. '3, is engaged. with the tubes, butthe pad is angularly disposed, haying; what may be termed-a lead surface146, as shown in Figs 2, which results in the appearance in theillustration of Fig. 3. Similarly the bending pad 30 has a lead surface148 (Fig. 9).

Thev grooves in the bending pads are, formed substan-. tially on theradii of the tubes to be received therein, andthe center to centerdistances are substantially equal to the center to center distances ofthe tubes or,. in other words, substantially equal to the diameter ,ofthe tubes. The intervening webs 138 and 141 extend from-the lowermost-part of the grooves 21- distauce less than the radius or, in otherwords, terminate short of a plane containing; thenentral axis .of. thetubes. receivedtherein. Accordg y; when several tubes areproperly-positioned within laterally as they the grooves they makecontact with each other substantially along lines lying in a planecontaining their neutral axes. The outside surfaces of the outermosttubes of both bending pads are supported by the side portions 136, 137and 142 and 143. Therefore, it will be seen that the tubes support eachother by interengaging with each other and are held and prevented fromflattening are bent around the respective arbors.

At the beginning of a cycle of operation the swinging arm 50 is in theposition as shown in Fig. 1; the bending assembly on the end of the armis in open position, as shown in Fig. 13. In said open position, theassembly has been rocked counter-clockwise, as Fig. 13 is viewed, fromthe position shown in Fig. 2 and the bending pad sub-assembly has beenrocked counter-clockwise, as Fig. 13 is viewed, and held elevated by thetoggle levers 90 and 91. The arbor 16 is retracted, as shown in Fig. 16.Thus, there is a clearance for shifting the tubes laterally in positionover the arbor 72 and under the arbor 16. The leading ends of the tubesmay be engaged by the clamp and trailing portions of the tubes by clip4. With the tubes thus in position, the apparatus is set for a bendingoperation. Oil is introduced into the cylinder 118 to rock the sprocket110 which, through the chain 75, rocks the assembly on the end of thearm member 52 clockwise to the position shown in Fig. 2. The rod 100 isshifted to rock the lever 78 clockwise to set the sub-assembly to theposition shown in Fig. 2. Thus, the bending pad 85 is set to a pre-bendor overbend position relative to the fixed pad 73 and arbor 72. Thearbor arm 18 is shifted from the position shown in Fig. 16 to theposition shown in Figs. 1 and 9, so that the tubes are caused to beengaged between the arbor and the bending pad 30. This is also anoverbend position with reference to the fixed pad 23.

and the bearing 31 for shown concentric with the arbor. a bend, thebending assembly on appears as shown in Fig. 5.

Now, it will be observed that two bends have been made in the tubes, oneshown at d (Fig. 12) about the arbor 16 and one shown at e (Fig. 5)about the arbor 72. The 'tubes are tightly engaged about the arbors, andfurthermore engaged in the grooves in the sliding bending pads.Therefore, to remove the several bent tubes, the machine has to beopened and the following things take place: The bending assemblyembodying the unit 70 is shifted from the position shown in Fig. 5 tothe position shown in Fig. 13, this being accomplished by actuating arm115, rod 116, cylinder motor 118, chain 75, and sprocket 74. The rod 100is shifted and the lug 105 engages and rocks the'lever 78 to shift thepad 85 from closed position, as shown in Fig. 5, to open position asshown in Fig. 13. The arm 18 for the arbor 16 is rocked from theposition shown in Fig. 12 to the position shown the bending pad in theposition At the completion of the end of the arm in Fig. 16. In thisaction the lug 36 shifts from locking The arm 50 is now swung on itsaxis by cylinder motor 48, rack 46, and gear 45 through substantially180, as Fig. l is viewed, if a bend of 180 is desired. In this actionthe length of tubing being supplied to the machine and lying on thesupporting arm 5 is stabilized as the arm 5 swings up about its pivot 6.As the arm 50 swings the bending assembly on the end of the arm is heldrelatively fixed by means of the chain 75 and associated parts so thatthe bending pad 85 bends the tubes about the arbor 72. The arm 38 withits bending pad 30 is swung about its bearing 31 by reason of its roller40 lying in the cam slot 41, thus causing the pad 30 to bend the tubesabout the arbor 16. The shape of the cam groove 41 is determined so asto move the pad 30 about the arbor 16 substantially at the same rate ofangular movement as the bending pad 85 moves about the arbor 72. It willbe appreciated that some tube is consumed in the bend about the arbor16. Thus, the distance between the arbor 16 and the arbor 72 must vary.The arbor 72 must traverse a form of involute curve. The axis x ofarm'50 is preferably located so that the radial distances from thecenter x-to the involute curve at various points along the curve havesubstantially a minimum amount of variation. If the involute curve had acenter, which it does not, it could be visualized that the center x isplaced near the center of the involute. The springs 56 constantly urgethe outer part of the arm inwardly with the rollers 63 riding on the cam65, the surface of which is formed to control the movement of the arbor72 substantially along the involute curve. In other words, by a properlocation of the center x of arm 50 the control required of the cam 65 isminimized. If the arbor 72 moved about the axis y of the arbor 16 on thefixed radius of the position shown in Fig. 1, it would traverse the arcb. However, it actually traverses a form of involute as shown by thecurvea, due to the shape of the cam 65. At the completion of a bend, thebending pad 30 and associated parts are substantially as illustrated inFig. 12. It will be appreciated that during the operation justdescribed, the arbor arm 18 through its lug 36 holds the plate 32position, as shown in Fig. 12, thus releasing the plate 32, and the camelement 17 on arm 18 engages the roller 42 which rocks lever 38clockwise (Fig. 16) about the axis of pivotal mounting 31, and the plate32 counterclockwise about its axis 33 thus raising the pivotal mounting31 for the bending pad 30, and the roller 40 of the arm 38 moves intothe angular portion 41a of the cam slot to support the bending pad andhold it elevated as shown in Fig. 16. Now the several tubes'may beremoved by shifting the same axially relative to the arbors.

The next movement is to return the swinging arm to its starting positionin which action it moves clockwise through the arcuate movementindicated in Fig. 1, and in this action the roller 42 moves olf the cam17 so that the plate 32 drops into position with the abutment 34striking abutment 35, thus positioning the axis of the bending pad 30concentrically with the arbor 16. The parts are now in their initialposition ready for the several tubes to be advanced and again placed inposition between the arbors and their respective bending pads.

As previously stated, it is necessary to support the tubes to preventthem from flattening; particularly when they are bent on a short radius.Therefore, the bending pads 30 and 85 are grooved as shown to lendsupport to each tube. I Moreover, the outside tubes are supported attheir median line or neutral axis and each tube contacts another alonglines lying in a plane containing the neutral aXis of each tube, andthus each tube obtains support from its neighbor.

Further, when the bending pads are thus grooved to support the tubes,the area of the surface to surface engagement between the bending padsand the tubes is sub: stantially increased and this is one of thereasons why the bending pads 30 and 85 are slidably mounted carriers 28and 84. Accordingly, are moved about the arbors, they do not slide onthe tubes. The pads 30 and 85 slide on their supports or carriers 28 and84 against the action of the respective springs 130 and 86. Thedisplaced positions of the pads 30 and 84,

with respect to their carriers or supports, following a bend, are shownin tended against the action of the spring and the pad 84 is extendedagainst the action of the spring 86. It might be stated that withoutthis sliding action of the bending pads that the friction on the tubeswould be so great as to distort or deform the tubes, to even pull thetubes out of the clamp and to cause metal of the tubes to be scraped offand deposited in the groove of the pads,

introduction of friction required to be in addition to the overcome inthe We claim: 1. In an apparatus for bending a plurality of work piecesof elongated form, such as tubes, a bending form operation of themachine.

with smooth forming surfaces, a bending pad, the bend- J on their whenthe bending pads Figs. 5 and 12. The pad 30 is exing form and thebending pad adapted to have a plurality of workpieces disposedtherebetween, the bending pad having a plurality of grooves therein, onefor each work piece, and adapted to engage the work pieces with a workpiece in each groove, the grooves being formed to fit the individualwork pieces and the pad having web portions between its grooves whichterminate short of a plane containing the neutral axes of the workpieces, so that the work pieces engage and support each other alonglines of contact lying substantially in said plane, side portions on thebending pad projecting at least to said plane to support the outer sidesof the outermost work pieces, whereby all work pieces are supportedthereby, and means for moving the bending pad relative to the bendingform to bend the work pieces on the bending form.

2. In an apparatus for bending a plurality of work pieces of elongatedform and circular in cross section, such as tubes, a bending form withsmooth forming surfaces, a bending pad, the bending form and the bendingpad adapted to have a plurality of work pieces disposed therebetween,the bending pad having a plurality of grooves therein, one for each workpiece, and adapted to engage the work pieces with a work piece in eachgroove, each groove being formed on a radius substantially the same asthe radius of the work piece received therein and the center to centerdistances between the grooves being substantially equal to the outsidediameter of the work pieces, the grooves having a depth less than theradius of the work pieces so that the work pieces engage and supporteach other along lines of contact lying substantially in a planecontaining their neutral axes, the pad having side portions defining theoutermost grooves which project at least to a, plane containing theradial centers of the grooves, to thereby engage and support theoutermost faces of the two outermost work pieces, so that all workpieces support one another against flattening, and means for moving thebending pad relative to the bending form to bend the work pieces on thebending form.

3. In an apparatus for bending a plurality of like work pieces ofelongated form and circular in cross section, such as tubes, an arbor,with smooth forming surfaces, a bending pad, the arbor and the bendingpad adapted to have a plurality of work pieces disposed therebetween,the bending pad having a plurality of grooves therein, one for each workpiece, and adapted to engage the work pieces with a work piece in eachgroove, the grooves being formed substantially on the radius of the workpieces and the center to center distance between the grooves beingsubstantially equal to the diameter of the work pieces,

the grooves being defined by intervening web portions of an extent lessthan the radius on which the grooves are formed, whereby the work piecesengage and support one another along lines of contact lyingsubstantially in a plane containing their neutral axes, the bending padhaving side portions defining the outermost grooves and saidsideportions having an extent at least substantially equal to the radiusof the grooves, whereby to contact and support the outside surfaces ofthe outermost work pieces substantially in said plane, and means forcausing the bending pad to move about the arbor to bend the work pieceson the arbor with the work pieces supported against flattening.

4. In an apparatus for bending a plurality of like work pieces ofelongated form and circular in cross section, such as tubes, a bendingform, a supporting element, the bending form and supporting elementadapted to have the work pieces disposed therebetween, a forming padmounted on. the supporting element for sliding movement onthe'supporting element in a direction lengthwise of the work pieces, thebending pad having grooves therein, one for each work piece, and adaptedto engage the work pieces with a work piecein each groove, the groovesbeing formed to fit having web portions defining the grooves whichtermithe individual work pieces, the pad 8 V nate short of a planecontaining the neutral axes of th work pieces so that the work piecesengage and support each other along lines of contact lying substantiallyin said plane, the pad having side portions defining the outermostgrooves to engage and support the outside surfaces of the outermost workpieces substantially in said plane, and means for moving the supportingelement relative to the bending form to cause the pad to bend the workpieces on the surface of the bending form with the pad sliding on thesupporting element and engaging, the work pieces in non-sliding manner.

5. The apparatus as described in claim 4 characterized in that thegrooves in the bending pad are formed substantially on the radius of thework pieces and are positioned at center to center distancessubstantially equal to the outside diameter of the work pieces.

6. The apparatus as described in claim 4 characterized in that thegrooves in the bending pad are formed substantially on the radius of thework pieces and are positioned at center to center distancessubstantially equal to the outside diameter of the work pieces, andfurther characterized in that the pad has web portions between thegrooves allowing the tubes to contact each other along said lines ofcontact.

7. An apparatus for bending a work piece of elongated form, such astube, into a coil of serpentine form'having a succession of reversebends comprising, a supporting frame, a first arbor mounted on theframe, an arm pivotally mounted on the frame with its pivot adjacentsaid arbor, a second arbor on the arm removed from the pivot thereof, abending pad pivotally mounted adjacent the first arbor, a bending padpivotally mounted adjacent the second arbor, the arbors and pads adaptedI to have a substantially straight work piece positioned be.-

tween the respective arbor and pad with the work piece extendingtransversely of the axes of the arbors, means for holding the leadingend of the Work piece in fixed position, spring means for yieldablyurging the second arbor radially inwardly toward the pivot of said arm,means for swinging the arm on its pivot, means for causing the bendingpads to move about their respective arbors as the arm swings to bend thework piece about the two arbors, a cam device positioned adjacent thepivot of said arm, and an element connected to the second arbor andriding on said cam device as the arm.

swings, said cam device being formed to control theradial inwardmovement of the second arbor, as the arm swings, to an extentsubstantially corresponding to that; required by the shortening of thework piece because of the wrap of the work piece about the first arbor.

8. An apparatus for bending a plurality of work piecesof elongated form,such as tubes, into a coil of serpentine form having a succession ofreverse bends comprising, a supporting frame, a first arbor mounted onthe frame, an arm pivotally mounted on the frame with its pivot adjacentsaid arbor, a second arbor on the arm removed from the pivot thereof,the arbors having smooth forming surfaces, a bending element pivotallymounted adjacent the first arbor, a bending element pivotally mountedadjacent the second arbor, the arbors and elements adapted to have aplurality of substantially straight work pieces positioned between therespective arbor and bending element and extending transversely of.

the axes of the arbors, a bending pad slidably mounted on each bendingelement and adapted to engage the work pieces, means for swinging thearm and location so that the work pieces engage each other along linesofcontact lying substantially in. a plane containing their neutral axes,said grooves having side poron its pivot, andmeans for causing thebending elements with the pads-v thereon to move about their respectivearbors. as the, arm swings to thereby bend the work pieces about bothpads having a non-sliding con-.

tions which engage and support the outermost work pieces on their outerfaces substantially in said plane.

9. The apparatus as described in claim 8 characterized in that thebending pad adjacent the arbor on the arm is pivotally mounted relativeto said arbor, means for rocking the pad to provide clearance forinsertion and removal of the work pieces, and means for rocking the padinto engagement with the work pieces and for locking the pad in saidengaged position.

References Cited in the file of this patent UNITED STATES PATENTS 10Gail May 31, I921 Kardong Oct. 14, 1924 Oddie Nov. 9, 1926 NowakowskiMar. 25, 1930 Maxwell et al. May 23, 1933 Meyer Feb. 20, 1934 Mason Jan.8, 1935 Sachleben May 11, 1937 Weightman June 6, 1944 Lancaster Mar. 20,1945 Payne June 28, 1949 Armstrong et al Aug. 28, 1951 Payne Oct. 13,1953

